Preheat your oven to 400°F (200°C).
Toss the cubed sweet potatoes with 1 teaspoon of olive oil and a pinch of salt, then spread them on a baking sheet.
Roast the sweet potatoes for 20-25 minutes until tender and slightly browned.
While potatoes roast, season the sirloin steak with salt and pepper.
Grill the steak over medium-high heat for 4-5 minutes per side, or until it reaches your desired level of doneness.
Remove the steak from the grill and let it rest for at least 5 minutes before slicing thinly against the grain.
In a small jar or bowl, whisk together the remaining teaspoon of olive oil, balsamic vinegar, and lemon juice to create the dressing.
Place the arugula, cherry tomatoes, and roasted sweet potatoes in a large bowl.
Drizzle the dressing over the vegetables and toss gently to coat.
Top the salad with the sliced steak and serve immediately.